1. Field of the Invention
The present invention relates to a pump for circulating coolant between a radiator and the cylinder block of an automotive internal combustion engine.
2. Disclosure Information
Automotive designers have gravitated toward centrifugal pumps for automotive engines. Such pumps are characterized in part by the placement of their fluid inlets and outlets along the radial edge of a centrifugal impeller. Centrifugal pumps are typically difficult to package because of their large size, and they are relatively inefficient because of the large amount of power needed to perform work on the coolant. Moreover, it is difficult to change the flow output, in other words, the volume and pressure of the flow, without expensive redesigning of the impeller and its housing. U.S. Pat. No. 1,370,823 discloses a water pump and aerator for a cooling system of an engine in which a multiple propellers are used with some having air inlets to entrain atmospheric air into the liquid coolant. The pump of the ""823 Patent does not have inlet and outlet flow control stators covering substantially the entire flow channel and the discharged fluid, as with the intake fluid flows with a mixed flow and this pump would therefore be expected to operate at only minimum efficiency.
The inventors of the present automotive coolant pump have determined that an efficient pump may be constructed with a mixed flow transition section followed by a transitional stator in advance of an axial propeller, which is itself flowed by a flow regenerator so as to allow the fluid to be discharged in a purely axial direction. A pump according to the present invention will overcome problems noted with both centrifugal pumps and the pump of the ""823 Patent.
An internal combustion engine includes a cylinder block structure, a coolant intake port formed in the cylinder block structure, a radiator, and a liquid coolant pump mounted to the cylinder block structure for moving coolant from the radiator into the coolant intake port. The coolant pump comprises an inlet connected with the radiator, and an axially-directed rotary pumping element for producing an axially-directed flow of coolant, with the rotary pumping element being attached to a sealed driveshaft. An upstream transitional stator is mounted proximate rotary pumping element, between the pumping element and the inlet. This upstream stator straightens the flow entering through a transitional mixed flow section extending between the inlet and the upstream transitional stator. After passing through the rotary pumping element, the flow passes through a downstream flow straightening stator mounted proximate to rotary pumping element between the pumping element and the coolant intake port. The upstream and downstream stators preferably comprise unitary structures, with each having a plurality of curved vanes attached to a common hub and terminating in a common peripheral ring shroud. The downstream flow straightening stator functions as a flow regenerating stator which recovers momentum directed in non-axial directions and converts non-axial motion of the fluid to axial motion with increased pressure and velocity. Each of the stators uses curved vanes rather than straight vanes. The stators may comprise stamped or cast structures made of metals or plastic composites.
A coolant pump according to the present invention may be powered directly by an engine, such as by the engine""s crankshaft or camshaft, or could be powered by an electric motor or hydraulic motor attached to the drive shaft extending through the pump and mating with a common hub which is junction for a plurality of curved blades for the rotary pumping element, or propeller, with the blades terminating in a common peripheral ring shroud.
According to another aspect of the present invention, a method for providing liquid coolant to an internal combustion includes the steps of drawing coolant from a radiator into a coolant pump, passing the coolant through a mixed flow transition section within the pump and thereby changing the flow from primarily a radially directed flow to primarily an axially directed flow, and then passing the coolant through a transitional stator to increase the axially directed flow component. Then, work is performed upon the coolant with an axially directed, rotary pumping element and the coolant is then passed through a flow regenerator to increase the axially directed flow component. Finally, the coolant is passed into a coolant intake port formed in a cylinder block structure of an engine.
It is an advantage of a coolant pump according to the present invention that an engine may be equipped with a pump which performs more efficiently and with lower power consumption.
It is a further advantage of the present invention that flow leaving a coolant pump according to the present invention will be primarily axially directed and will flow into an engine at higher velocity and greater pressure than is possible with conventional automotive centrifugal coolant pumps.
It is a further advantage of the present invention that a coolant pump according to this invention will function at a lower noise level than known coolant pumps.
It is a further advantage of the present invention that a coolant pump according to this invention may be made of non-metallic materials providing superior durability, as well as cost advantages.
It is a further advantage of the present invention that a coolant pump according to this invention may be easily reconfigured to revise the pump""s operating characteristics, such as the flow volume and output pressure, by changing the shape, pitch, and number of blades on the pump""s propeller.